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///M3 Forum The BMW E46 ///M3 is the M version E46 and puts out an amazing 333 HP and 262 lb-ft of torque at stock specs! There are an amazing amount of modifications for both the coupe and convertible models so read up and get started modifying your cars today!

if I had an M3, royal purple products wouldn't come anywhere near it..

really - how often do you have to change the diff fluid? maybe 3-4 times over the life of the car? I feel the same way with coolant. Yeah, it's an extra $20 for the BMW stuff - but that's spread out over two years. I've seen the damage from using cheap fluids and it's just not worth it. BMW stuff is formulated exactly for your car, you don't have to guess or hope it will work.

i apologize for bumping such an old thread.. but has anyone tried the Redline Limited Slip Friction Modifier?? If so, any thoughts or reviews about it?
I recently changed my diff fluid with RL 75W-140 and i started hearing the whine. My shop recommended this:http://www.redlineoil.com/product.aspx?pid=41&pcid=4

OEM! I used a few years ago and its still good. The BMW limited slip diff is very picky and likes the FM booster...and no you can't by the booster by itself. If you swap the locker, you can use different fluid.